A standard mixing valve has a housing in which is contained a connector block to which are connected hot- and cold-water input lines and a mixed-water output line and on which is mounted a valve cartridge. A lever or the like connected to the cartridge can move in one direction to vary the volume rate of flow from the input lines to the output line, and in a normally transverse direction to vary the mix ratio between the input lines, thereby controlling output temperature. Typically the housing has a decorative outside finish and is intended to cover and protect the connecting block and valve cartridge. The connecting block itself is normally fixed to some kind of plate, which term is here intended to include a deck, counter, or wall panel, and the housing is in turn fixed to the connector block.
As described in German patent document 3,120,210 filed May 21, 1981 by A. Gottwald, a variation on this system is shown where the valve cartridge is carried at the outer end of an L-shaped housing whose inner end is itself bolted to the deck plate. In this system as in virtually all the prior art, the connection of the housing to the connector block is visible from outside, marring the appearance of the valve and creating a trap for dirt. Furthermore assembly of these system is relatively complex, often entailing connecting several pieces together, then fitting them to the housing, and finally securing the housing in place on the connected pieces.